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<p>Hello Gerald,</p>
<p>Thank you very much for your reply.</p>
<p>The model is small (302 variables).</p>
<p>Setting parameter age limit to -1 does not seem to deactivate
scip internal pricing (442 variables from our pricing versus 66334
from scip). <br>
</p>
<p>Also, let me specify that at the beginning of each pricing phase<em>
</em><em style="font-style: normal; color: rgb(106, 106, 106);
font-family: arial,sans-serif; font-variant-caps: normal;
letter-spacing: normal; text-align: left; text-indent: 0px;
text-transform: none; white-space: normal; word-spacing: 0px;
-moz-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">PRICERREDCOST,
</em>we displayed the number of variables previously added by our
pricer and the result of SCIPgetNPricevarsFound. During several
iterations, the two numbers were the same. But at some point the
second number becomes higher than the first, and the difference
between the two numbers increases until the end of the
branch-and-price.<br>
</p>
<p>The statistics displayed at the end (with scipprintstatistics)
showed that scip's pricer is very fast (0.03s), so we not longer
expect to gain any speed-up there. <br>
</p>
<p>But we would still like to deactivate it if possible, to help us
investigating the following issue : Let's consider two disjoint
sets of columns S1 and S2, and their union Sall (= S1 U S2). We
are trying to understand why in our branch-and-price, adding Sall
leads to a worse final solution than adding S1 example. Therefore
we are carefully rechecking our code and we would like to
deactivate scip's pricer if possible.</p>
<p>Best regards,</p>
<p>Sandra<br>
</p>
<br>
<div class="moz-cite-prefix">Le 25/06/2018 à 19:19, Gerald Gamrath a
écrit :<br>
</div>
<blockquote type="cite"
cite="mid:e9054c09-0e83-0763-a649-1c6f19d31bd2@zib.de">Dear
Sandra,
<br>
<br>
I don't think that SCIPgetNPricevarsFound returns what you are
interested in. As far as I can see, this is the total number of
variables that were added to the to the pricestore. This may be
variables "priced" by SCIP, but also the variables you priced, as
well as all variables in your original formulation, that go
through the pricestore once to enter the LP. Perhaps your original
formulation is quite large?
<br>
<br>
Setting the age limit to -1 should normally do the trick. There
are other things like "lp/cleanupcols(root)", but those are
disabled by default.
<br>
<br>
When you look at the statistics after solving ("disp stat" in the
interactive shell or SCIPprintStatistics()), you should see how
many variables are really added by your pricer and by the internal
SCIP pricing ("problem variables"). Is there a nonzero number for
the latter?
<br>
<br>
Best,
<br>
Gerald
<br>
<br>
On 25.06.2018 18:28, Sandra Ulrich Ngueveu wrote:
<br>
<blockquote type="cite">Hello,
<br>
<br>
We are doing a Branch-and-Price with SCIP. Using function
"SCIPgetNPricevarsFound", we realized that a very higher number
of variables were "priced" by scip, compared to the number of
columns that we explicitely added (127253 instead of 475).
<br>
<br>
We would like to deactivate such internal pricing (which
according to some forum is related to column aging) just to
verify if the code would be faster for our specific problem. We
tried setting parameter lp/colagelimit to -1, but the number of
additional pricedvars declared by scip remained unchanged.
<br>
<br>
Could you please tell us if there is another parameter we could
activate or deactivate to achieve the desired behaviour ?
<br>
<br>
Best regards,
<br>
<br>
Sandra U. Ngueveu
<br>
<br>
</blockquote>
<br>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Maître de Conférences / Associate Professor
-----------------------------------------------
<a class="moz-txt-link-freetext" href="http://homepages.laas.fr/sungueve">http://homepages.laas.fr/sungueve</a>
-----------------------------------------------
<a class="moz-txt-link-abbreviated" href="mailto:ngueveu@laas.fr">ngueveu@laas.fr</a>
Equipe ROC
LAAS-CNRS
7 avenue du Colonel Roche
31031 Toulouse Cedex 4 - France
-----------------------------------------------
<a class="moz-txt-link-abbreviated" href="mailto:sandra.ngueveu@enseeiht.fr">sandra.ngueveu@enseeiht.fr</a>
Département GEA
INP-ENSEEIHT
2 rue Charles Camichel
31071 Toulouse - France</pre>
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